CONFIG_CPU_FREQ_PMAC64 is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

Support for some Apple G5s

modulename: cpufreq_64.ko

configname: CONFIG_CPU_FREQ_PMAC64

Linux Kernel Configuration
└─>Platform support
└─>CPU Frequency drivers
└─>Support for some Apple G5s
In linux kernel since version 2.6.15 (release Date: 2006-01-02)  
This adds support for frequency switching on Apple iMac G5,
and some of the more recent desktop G5 machines as well.

source code:
arch/powerpc/platforms/powermac/cpufreq_64.c
selects
CONFIG_CPU_FREQ_TABLE

depends
CONFIG_CPU_FREQ
CONFIG_PPC64
CONFIG_PPC_PMAC